Monday, 15 April 2013

Monitoring S3 uploads for a real time data

        If you are working on Big Data and its bleeding edge technologies like Hadoop etc., the primary thing you need is a "dataset" to work on. So, this data can be reviews, blogs, news, social media data (Twitter, Facebook etc), domain specific data, research data, forums, groups, feeds, fire hose data etc. Generally, companies reach the data vendors to fetch such kind of data.

        Normally, these data vendors dump the data into a shared server kind of environment. For us to use this data for processing with MapReduce and so forth, we move them to S3 for storage first and processing next. Assume, the data belong to social media such as Twitter or Facebook, then the data can be dumped according to the date format directory. Majority of the cases, its the practice.
Also assuming 140-150GB /day being dumped in a hierarchy like 2013/04/15 ie. yyyy/mm/dd format, stream of data, how do you 
-  upload them to s3 in the same hierarchy to a given bucket?
-  monitor the new incoming files and upload them?
-  save the space effectively on the disk?
-  ensure the reliability of uploads to s3?
-  clean if the logging is enabled to track?
-  re-try the failed uploads?

These were some of the questions, running at the back of my mind, when I wanted to automate the uploads to S3. Also, I wanted 0 human intervention or at-least the least!
So, I came up with 
- s3sync / s3cmd.
- the python Watcher script by Greggory Hernandez, here 
A big thanks! This helped me with monitoring part and it works so great!
- few of my own scripts.

What are the ingredients?
  •  Installation of s3sync. I have just used one script of s3cmd here and not s3sync in real. May be in future -- so I have this.
  • Installation of Watcher.
  • My own wrapper scripts.
  • cron
Next, having set up of the environment ready, lets make some common "assumptions".
  • Data being dumped will be at /home/ubuntu/data/ -- from there it could be 2013/04/15 for ex.
  • s3sync is located at /home/ubuntu
  • Watcher repository is at /home/ubuntu
Getting our hands dirty...
  • Goto Watcher and set the directory to be watched for and corresponding action to be undertaken.
  • Create a script called to upload to s3 in s3sync directory as below.
    • The variables you may like to change is s3bucket path in "s3path" in
    • This script will upload the new incoming file detected by the watcher script in the reduced redundancy storage format. (you can remove the header -- provided you are not interested to store in RRS format)
    • The script will call s3cmd ruby script to upload recursively and thus maintains the hierarchy ie. yyyy/mm/dd format with files *.*
    • It will delete the file successfully uploaded to s3 from the local path -- to save the disk space.
    • The script would not delete the directory, as it will be taken care by yet another script, which acts as a backup for the failed uploads to be uploaded again to s3.
  • Create a script called which will upload the failed file uploads.
    • This script ensures that the files that are left over from (failed uploads -- this chance is very less. May be 2-4 files/day. -- due to various reasons.), will be uploaded to s3 again with the same hierarchy in RRS format.
    •  Post successful upload, deletes the file and hence the directory if empty.
  • Now, more dirtiest work -- Logging and cleaning logs.
    • All the "echo" created in can be found in ~/.watcher/watcher.log when the is running.
    • This log helps us initially and may be later too, to backtrack errors or so.
    • Call of duty - Janitor for cleaning logs. To do this, we can use cron to run a script at sometime. I was interested to run - Every Saturday at 8.00 AM
    • Create a script to clean log as "" in /home/ubuntu/s3sync
  • Time for cron
    • All set! logging clean happens every Saturday 8.00 AM and re-upload script runs for the previous day, to check if files exist and does the cleaning accordingly.
  • Let's start the script
So, this assures successful uploads  to S3. 
My bash-fu with truth! ;)
Happy Learning! :)

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